Author traces the rise of deadly viruses

Maggie Galehous, Houston Chronicle

By Maggie Galehouse

Updated 2:43 pm, Thursday, December 20, 2012

In "Spillover," David Quammen writes about diseases that move from animal to human populations, often with deadly results. Scientists have linked the ebola virus to gorillas, such as this mountain gorilla in Rwanda.
Photo: Tom Gandy

In "Spillover," David Quammen writes about diseases that move from...

In "Spillover," David Quammen writes about diseases that move from animal to human populations, often with deadly results. Scientists have linked the ebola virus to gorillas, such as this mountain gorilla in Rwanda.
Photo: Tom Gandy

In "Spillover," David Quammen writes about diseases that move from...

In "Spillover," David Quammen writes about diseases that move from animal to human populations, often with deadly results. Scientists have linked the ebola virus to gorillas, such as this mountain gorilla in Rwanda.
Photo: Tom Gandy

In "Spillover," David Quammen writes about diseases that move from...

In "Spillover," David Quammen writes about diseases that move from animal to human populations, often with deadly results. Scientists have linked three viruses ? SARS, Nipah and Hendra ? to bats.
Photo: GREG WOOD, Staff

In "Spillover," David Quammen writes about diseases that move from...

HIV passed from a chimp to a human early in the last century, author David Quammen said.
Photo: BORIS HEGER, STR

HIV passed from a chimp to a human early in the last century,...

In "Spillover," David Quammen writes about diseases that move from animal to human populations, often with deadly results. Scientists have linked malaria to macaques (monkeys) in Borneo.
Photo: Richard Kirby, HO

In "Spillover," David Quammen writes about diseases that move from...

"Spillover" by David Quammen
Photo: Xx

"Spillover" by David Quammen

HIV passed from a chimp to a human early in the last century, author David Quammen said.
Photo: Lynn Donaldson

On Feb. 21, 2003, physician Liu Jianlun checked into Hong Kong's Metropole Hotel. Liu had been feeling fluish for days but thought he was well enough to attend his nephew's wedding the next day.

He wasn't.

When he awoke the next morning in room 911, Liu felt so poor he decided to skip the wedding and head for the nearest hospital. By the time he checked out of the Metropole Hotel - where he had sneezed and coughed and perhaps vomited in the ninth-floor corridor - Liu had infected 16 guests and a hotel visitor with severe acute respiratory syndrome.

This Chinese physician, who died a few weeks later, was one of the super-spreaders of SARS, a virus that infected more than 8,000 people and killed about 700 over several months.

His is one of dozens of lives that flicker to life in David Quammen's recent book, "Spillover: Animal Infections and the Next Human Pandemic," which traces the rise of a handful of deadly viruses including SARS, Ebola, AIDS, Hendra and Nipah. As Quammen explains, all are zoonotic diseases: infections transmitted from animals to humans.

The great thing about emerging diseases is that each one begins with a mystery story, Quammen said before a recent talk at Houston's Asia Society Texas Center.

"Viruses are invisible; that's what makes them so scary, but they do have their limits," Quammen said. "They're not preternatural. Ebola, for example, can't travel through the air on a sneeze, like SARS. Ebola doesn't ride airplanes well."

Weaving the human stories of scientists, victims and survivors together with the far-reaching origins of each virus, Quammen, 64, connects the dots back to the moment of spillover: when the pathogen first passed from an animal to a human.

Scientists have linked the virus that causes AIDS to chimpanzees in Cameroon, malaria to macaques (monkeys) in Borneo, Ebola to gorillas and three viruses - SARS, Nipah and Hendra - to bats.

"Why are bats linked to so many viruses?" someone in the Asia Society audience asked.

"One school of thought is that bats are so diverse; they account for one in every four species on Earth," Quammen answered. "One-hundred thousand might roost together at one time. And a bat might live 18 to 20 years."

As "Spillover" explains, the Hendra virus, which affects the respiratory and nervous systems, was transmitted to humans from horses that were infected by bats. In a suburb of Brisbane, Australia, in 1994, a pregnant mare grazed in a field with a mature fig tree, where she probably sought shade. Bats roosted on the tree and, presumably, the mare came into contact with guano or fruit remnants the bats had dropped. The mare brought the virus back to the other horses at her stable, and very soon, horses and some of their human handlers started dying.

In the chapter on AIDS, Quammen follows the virus from 1980 - when scientists in Los Angeles and New York began noticing a pneumonialike disease among gay men that their immune systems couldn't fight - to 1908, when the spillover first occurred.

"HIV passed from a chimp in southeastern Cameroon to a human sometime in the early 20th century," Quammen said. "In passing from chimp to human, that virus had no intentionality. It just happened to be there. But it turns out to have been a very good career move for that virus. It went from that single chimp, a declining species, to infecting about 63 million people in the world; 30 million are now dead."

Quammen's overarching thesis is that spillovers occur because of human disruption and connectivity.

"We need to recognize that there are very few places on this planet where people haven't been," Quammen told me. "We're cutting down trees, clearing forests for settlement, killing and eating many of the animals in those places. We're capturing and transporting animals. We're shaking things loose, dislodging viruses from their accustomed hosts and offering ourselves as an alternative."

Once a virus infects the human population, it can spread more rapidly than ever.

"We live at greater densities," Quammen explained. "We can fly from one continent to another in a matter of hours. Something that spills over in some tiny remote place has the opportunity of blanketing the world within 24 or 36 hours."

Which leads Quammen to his provocative conclusion: In ecological terms, humans can be considered an outbreak population. And the thing about outbreak populations is, they crash.

In 1960, there were 3 billion people in the world and, since then, each net addition of another billion has taken roughly 13 years, Quammen notes. Today, we have passed the 7 billion mark.

"The reason scientists are so vigilant toward single-strand RNA viruses, like the ones described in the book, is because they replicate abundantly and they mutate a lot, which means they generate a lot of genetic variation," Quammen told me. "Those are the perfect ingredients for Darwinian selection and adaptation."

The Next Big One - the next virus that could threaten the human population - could easily be an RNA virus, so named because its genetic material contains ribonucleic acid.

In recent months, Quammen said, a SARS-like virus has emerged from the Saudia Arabian peninsula and already killed a few people.

"Why are people paying such close attention?" Quammen asked. "Because SARS was so potentially devastating and this one is so closely related to SARS. Scientists all over the world have jumped on it and said that this is what The Next Big One could look like. The key is to catch it when it has killed one person as opposed to 30 million."

On Feb. 21, 2003, physician Liu Jianlun checked into Hong Kong's Metropole Hotel. Liu had been feeling fluish for days but thought he was well enough to attend his nephew's wedding the next day.

He wasn't.

When he awoke the next morning in room 911, Liu felt so poor he decided to skip the wedding and head for the nearest hospital. By the time he checked out of the Metropole Hotel - where he had sneezed and coughed and perhaps vomited in the ninth-floor corridor - Liu had infected 16 guests and a hotel visitor with severe acute respiratory syndrome.

This Chinese physician, who died a few weeks later, was one of the super-spreaders of SARS, a virus that infected more than 8,000 people and killed about 700 over several months.

His is one of dozens of lives that flicker to life in David Quammen's recent book, "Spillover: Animal Infections and the Next Human Pandemic," which traces the rise of a handful of deadly viruses including SARS, Ebola, AIDS, Hendra and Nipah. As Quammen explains, all are zoonotic diseases: infections transmitted from animals to humans.

The great thing about emerging diseases is that each one begins with a mystery story, Quammen said before a recent talk at Houston's Asia Society Texas Center.

"Viruses are invisible; that's what makes them so scary, but they do have their limits," he said. "They're not preternatural. Ebola, for example, can't travel through the air on a sneeze, like SARS. Ebola doesn't ride airplanes well."

Weaving human stories of scientists, victims and survivors together with the far-reaching origins of each virus, Quammen, 64, connects the dots to the moment of spillover: when the pathogen first passed from an animal to a human.

Scientists have linked the virus that causes AIDS to chimpanzees in Cameroon, malaria to macaques (monkeys) in Borneo, Ebola to gorillas and three viruses - SARS, Nipah and Hendra - to bats.

"Why are bats linked to so many viruses?" someone in the Asia Society audience asked.

"One school of thought is that bats are so diverse; they account for one in every four species on Earth," Quammen answered. "One-hundred thousand might roost together at one time. And a bat might live 18 to 20 years."

As "Spillover" explains, the Hendra virus, which affects the respiratory and nervous systems, was transmitted to humans from horses that were infected by bats. In a suburb of Brisbane, Australia, in 1994, a pregnant mare grazed in a field with a mature fig tree, where she probably sought shade. Bats roosted on the tree and, presumably, the mare came into contact with guano or fruit remnants the bats had dropped. The mare brought the virus back to the other horses at her stable, and very soon, horses and some of their human handlers started dying.

In the chapter on AIDS, Quammen follows the virus from 1980 - when scientists in Los Angeles and New York began noticing a pneumonialike disease among gay men that their immune systems couldn't fight - to 1908, when the spillover first occurred.

"HIV passed from a chimp in southeastern Cameroon to a human sometime in the early 20th century," Quammen said. "In passing from chimp to human, that virus had no intentionality. It just happened to be there. But it turns out to have been a very good career move for that virus. It went from that single chimp, a declining species, to infecting about 63 million people in the world; 30 million are now dead."

Quammen's overarching thesis is that spillovers occur because of human disruption and connectivity.

"We need to recognize that there are very few places on this planet where people haven't been," Quammen said. "We're cutting down trees, clearing forests for settlement, killing and eating many of the animals in those places. We're capturing and transporting animals. We're shaking things loose, dislodging viruses from their accustomed hosts and offering ourselves as an alternative."

Once a virus infects the human population, it can spread more rapidly than ever.

"We live at greater densities," Quammen explained. "We can fly from one continent to another in a matter of hours. Something that spills over in some tiny remote place has the opportunity of blanketing the world within 24 or 36 hours."

Which leads Quammen to his provocative conclusion: In ecological terms, humans can be considered an outbreak population. And the thing about outbreak populations is, they crash.

In 1960, there were 3 billion people in the world and, since then, each net addition of another billion has taken roughly 13 years, Quammen said. Today, we have passed the 7 billion mark.

"The reason scientists are so vigilant toward single-strand RNA viruses, like the ones described in the book, is because they replicate abundantly, and they mutate a lot, which means they generate a lot of genetic variation," Quammen said. "Those are the perfect ingredients for Darwinian selection and adaptation."

The Next Big One - the next virus that could threaten the human population - could easily be an RNA virus, so named because its genetic material contains ribonucleic acid.

In recent months, Quammen said, a SARS-like virus has emerged from the Saudia Arabian peninsula and already killed a few people.

"Why are people paying such close attention?" Quammen asked. "Because SARS was so potentially devastating and this one is so closely related to SARS. Scientists all over the world have jumped on it and said that this is what The Next Big One could look like. The key is to catch it when it has killed one person as opposed to 30 million."